小编j0n*_*1ve的帖子

我有一个有几个日期字段的表.例如,在缺陷表中,我有以下内容:dateAssigned,dateCompleted,dateResolved.我试图得到一个总结缺陷的查询:

           | Number Assigned | Number Completed | Number Resolved 
-----------------------------+------------------+-----------------
  Mar-2011 |      33         |        22        |        33        
  Apr-2011 |      10         |        11        |        22
  May-2011 |      22         |        66        |        46

等等

我想出以下内容无济于事:

SELECT year(d.dateAssigned)
      ,month(d.dateAssigned)
      ,COUNT(d.dateAssigned)
      ,COUNT(d.dateCompleted)
      ,COUNT(d.dateResolved)
  FROM defect d
  GROUP BY year(d.dateAssigned), month(d.dateAssigned)
  ORDER BY year(d.dateAssigned), month(d.dateAssigned)

这适用于汇总dateAssigned缺陷,但不适用于其他缺陷.我意识到这可能是因为我正在通过dateAssigned进行分组,但我不知道如何做到这一点.

任何帮助,将不胜感激.

我有一组对象,并且有兴趣从集合中获取特定对象.经过一番研究,我决定使用这里提供的解决方案:http: //code.activestate.com/recipes/499299/

问题是它似乎没有起作用.

我有两个类定义如下:

class Foo(object):
    def __init__(self, a, b, c):
        self.a = a
        self.b = b
        self.c = c
    def __key(self):
        return (self.a, self.b, self.c)
    def __eq__(self, other):
        return self.__key() == other.__key()
    def __hash__(self):
        return hash(self.__key())

class Bar(Foo):
    def __init__(self, a, b, c, d, e):
        self.a = a
        self.b = b
        self.c = c
        self.d = d
        self.e = e

注意:这两个类的相等性只应在属性a,b,c上定义.

该包装_CaptureEq在http://code.activestate.com/recipes/499299/还定义了自己的__eq__方法.问题是这种方法永远不会被调用(我认为).考虑,

bar_1 = Bar(1,2,3,4,5)
bar_2 = Bar(1,2,3,10,11)
summary = set((bar_1,)) …